1. Field of the Invention
The present invention relates to a manufacturing method of an ink-jet head having nozzle holes that eject ink droplets to a recording medium.
2. Description of Related Art
An ink-jet head has a nozzle plate in which many nozzle holes are formed. Ink droplets are ejected from the nozzle holes to a recording medium and land on the recording medium, so that a desired image is formed thereon. This type of ink-jet head also has ink passages that communicate with the respective nozzle hole. The ink passages are formed by laminating and bonding thin etched plates each having a plurality of communication holes formed therein. In order to bond an etched plate and a nozzle plate with good accuracy, according to a known technique, a gap material is buried in an adhesive film that is interposed between the etched plate and the nozzle plate (see Japanese Patent No. 3189844). In this technique, compression of the adhesive film upon pressure application is restricted to a constant amount due to a thickness of the gap material. Therefore, a space between the etched plate and the nozzle plate can be kept substantially equal.
However, a diameter of a communication hole, which is connected to a nozzle hole, is larger than a diameter of the nozzle hole. Thus, stress applied to an overhang which is formed around each nozzle hole of the nozzle plate and faces the communication hole inevitably concentrates on a portion of the nozzle plate, on the side facing the etched plate, corresponding to an outer edge of an opening of the communication hole. This makes it difficult to reliably prevent an adhesive such as the adhesive film from bulging into the communication hole. The adhesive, which has bulged into the communication hole, may further flow into the nozzle hole, and as a result may block the nozzle hole or cause troubles about ink ejection from the nozzle hole. In order to prevent such bulging of the adhesive, it is necessary to tightly control conditions such as a kind of adhesive, the amount of adhesive, a temperature in adhesion, pressure applied to the nozzle plate and the etched plate, and the like. In this case, however, a manufacturing cost is increased.